Abstract: An integrated micro-optical system includes at least two wafers with at least two optical elements provided on respective surfaces of the at least two wafers, at least one of the two optical elements being a spherical lens. The resulting optical system presents a high numerical aperture. One of the optical elements may be a refractive element formed in a material having a high index of refraction.

Abstract: An optical magnetic field sensor probe for detecting a magnetic field to be measured as an output light intensity, by disposing a polarizer, a magneto-optical device, and an analyzer mutually different in the transmission and polarization direction with respect to said polarizer, along the running direction of light, has an input optical fiber for feeding into to said polarizer through a first lens, and an output optical fiber for emitting an output light from said analyzer through a second lens, wherein said input optical fiber, said first lens, said magneto-optical device, said second lens and said output optical fiber are composed in a confocal optical system, and said first lens and said second lens are drum lenses.

Abstract: The present invention provides a magneto-optical member capable of ensuring an excellent light transmittance and an optical isolator using the same. A first one-dimensional magnetic photonic crystal having a magneto-optical thin film, and a second one-dimensional magnetic photonic crystal having another magneto-optical thin film are laminated so as to sandwich a dielectric thin film with a small refractive index having an optical length of &lgr;/4+m&lgr;/2 where &lgr; is a wavelength of light and m is 0 or a positive integer. Since a plurality of magneto-optical thin films are present as magnetic thin films and hence the total thickness of the magnetic thin films is increased, the Faraday rotation angle is increased. Also, a large light transmittance can be obtained because of the presence of the dielectric thin film with a small refractive index having (&lgr;/4+m&lgr;/2) thickness where the first and second one-dimensional magnetic photonic crystals are laminated.

Abstract: An interference modulator (Imod) incorporates anti-reflection coatings and/or micro-fabricated supplemental lighting sources. An efficient drive scheme is provided for matrix addressed arrays of IMods or other micromechanical devices. An improved color scheme provides greater flexibility. Electronic hardware can be field reconfigured to accommodate different display formats and/or application functions. An IMod's electromechanical behavior can be decoupled from its optical behavior. An improved actuation means is provided, some one of which may be hidden from view. An IMod or IMod array is fabricated and used in conjunction with a MEMS switch or switch array. An IMod can be used for optical switching and modulation. Some IMods incorporate 2-D and 3-D photonic structures. A variety of applications for the modulation of light are discussed. A MEMS manufacturing and packaging approach is provided based on a continuous web fed process.

Abstract: The present invention aims at providing a variable optical attenuator to achieve the reduction of the wavelength-dependency of the entire device, by optimizing the magneto-optical system of the variable optical attenuator by deliberating the wavelength-dependency of Faraday rotation angles. To this end, the variable optical attenuator according to the present invention comprises: a Faraday rotator for providing a variable Faraday rotation angle; and a polarizer and an analyzer arranged in front of and behind the Faraday rotator, respectively, wherein the angle formed between the optical axis of the analyzer and the optical axis of the polarizer is set such that the Faraday rotation angle at which the wavelength-dependency of the optical attenuation amount of the variable optical attenuator becomes the maximum, is brought to be substantially 0°, to thereby reduce the wavelength-dependency of the optical attenuation amount at the aforementioned Faraday rotation angle.

Abstract: An optical signal transmission system equipped with a magneto-optical modulator is provided. The magneto-optical modulator works to modulate an optical beam emitted from a light source and consists of a polarizer, a magneto-optical element, an analyzer, a dc field generator, a high-frequency field generator, and an impedance adjuster. The dc field generator works to apply a dc bias field to the magneto-optical element. The high-frequency generator is responsive to the high-frequency signal from said high-frequency signal generator to apply a high-frequency field to the magneto-optical element. The impedance adjuster works to adjust impedance of the high-frequency field generator for establishing effective transmission of the high-frequency signal to the high-frequency field generator, thereby increasing a modulation range up to frequencies higher than an upper limit of typical magneto-optical modulators.

Abstract: This invention discloses an optical circulator. The optical circulator includes a first set of optical components having a birefringent crystal, a pair of half wave plates and the Faraday rotator to separate and then polarize the light beam into projection-direction ready polarization components. These projection-direction ready polarization components are suitable for entering into a projection-direction optical-processing-optical device, e.g., a Wollaston prism, to generate the projecting-to-exit-port beam components. The circulator then employs a set of reciprocal components of the first set of optical components to carry out reciprocal polarization rotations and beam component merging processes to transmit an output beam to the exit port by projecting the beam components and the merged beam along the projecting-to-exit port direction.

Abstract: The present invention relates to a device for measuring a current in a magnetic field which includes a glass article wherein the glass may be an oxyfluoride glass or a bismuth oxide glass having a photoelastic coefficient of from about −0.2 to 0.2 at 546 nm. Further, the present invention relates to a method of measuring currents.

Abstract: A Faraday rotator whose Faraday's rotational angle has low temperature-dependency; a method for efficiently preparing the same; a magneto-optical element which makes use of the Faraday rotator and whose characteristic properties are not susceptive to temperature changes; and an optical isolator, which can be provided at a low price. A Faraday rotator consists of a garnet crystal represented by the following compositional formula and having a lattice constant of 12.470 ±0.013 Å: (Tb1−(a+b+c)LnaBibM1c)3(Fe1−dM2d)5O12 in the formula, Ln is an element selected from the group consisting of rare earth elements other than Tb; M1 represents an element selected from the group consisting of Ca, Mg and Sr; M2 is an element selected from the group consisting of Al, Ti, Si and Ge; and a to d are numerals satisfying the following relations: 0≦a≦0.5, 0<b≦0.2, 0≦c≦0.02 and 0≦d≦0.1.

Abstract: An apparatus which attenuates a light signal polarized in a first direction. The apparatus includes a polarization rotation unit and an output unit. The polarization rotation unit rotates the polarization of the light signal to produce a polarization rotated light signal having a polarization component in the first direction and a polarization component in a second direction which is substantially 90 degrees with respect to the first direction. The output unit passes, as an output signal, the polarization component in the second direction of the polarization rotated light signal and blocks the polarization component in the first direction. The polarization rotation unit includes an electromagnet and a permanent magnet which apply magnetic fields in specific directions with respect to the light path. Various yoke constructions are provided for the electromagnet and the permanent magnet.

Abstract: A semiconductor magneto-optical material includes a semiconductor dispersed with fine magnetic material particles and is characterized by exibiting magneto-optical optical effect at ordinary room temperature.

Abstract: An optical attenuation device to attenuate the intensity of incident light, comprising an optical attenuation unit including at least two different type magneto-optical optical attenuation elements coupled in a cascade together.

Abstract: An integrated micro-optical system includes at least two wafers with at least two optical elements provided on respective surfaces of the at least two wafers. An active element having a characteristic which changes in response to an applied field may be integrated on a bottom surface of the wafers. The resulting optical system may present a high numerical aperture. Preferably, one of the optical elements is a refractive element formed in a material having a high index of refraction.

Abstract: The present invention relates to a tunable optical filter having a variable wavelength characteristic of transmittance. The tunable optical filter includes first and second polarizers each having a transmission axis determining a polarization axis of transmitted polarized light, a birefringent element having an optic axis determining a phase difference given between two orthogonal components of transmitted polarized light, and a Faraday rotator for giving a variable Faraday rotation angle to transmitted polarized light. The birefringent element and the Faraday rotator are provided between the first and second polarizers.

Abstract: In all-optical networks, high speed optical switching and routing becomes one of the most important issues for interconnecting the transport network layers. This invention describes novel polarization-independent high speed optical switches using a digital Faraday rotator, which can also be used for various other optical switching devices. The basic digital Faraday rotator device is composed of (a) a semi-hard or hard iron garnet based magneto-optic crystal having bi-stable magnetization states at zero external magnetic field. (b) a wire winding around the crystal for changing the magnetization states by pulsed current having both fast rise time and short duration. (c) a circuit generating the required current pulses with both polarities.

Abstract: A light wavelength converting element having a periodic polarization inversion structure is produced in the following manner: a comb-shaped electrode and a plate electrode are attached to both surfaces of an MgO-LN substrate, and the MgO-LN substrate is immersed in an insulating liquid. In a state in which substrate temperature is at room temperature, the plate electrode is grounded and a pulse voltage of +0.75 kV, for example, is applied for one second such that the comb-shaped electrode has positive potential. Then, the comb-shaped electrode is grounded and a pulse voltage of −3.25 kV, for example, is applied for ten seconds such that the plate electrode has negative potential.

Abstract: A magneto-optical device using a rare earth iron garnet material, wherein the rare earth garnet material is expressed in the following formula: (BixGdyRzY3−x−y−z)(Fe5−wGaw)O12, wherein x is defined in a range of 0.84≦x≦1.10, y is defined in the range of 0.73≦y≦1.22, z is defined in the range of 0.02≦z≦0.03, and w is defined in the range of 0.27≦w≦0.32, and wherein R is at least one element selected from rare earth elements.

Abstract: An apparatus which attenuates a light signal polarized in a first direction. The apparatus includes a polarization rotation unit and an output unit. The polarization rotation unit rotates the polarization of the light signal to produce a polarization rotated light signal having a polarization component in the first direction and a polarization component in a second direction which is substantially 90 degrees with respect to the first direction. The output unit passes, as an output signal, the polarization component in the second direction of the polarization rotated light signal and blocks the polarization component in the first direction. The polarization rotation unit includes an electromagnet and a permanent magnet which apply magnetic fields in specific directions with respect to the light path. Various yoke constructions are provided for the electromagnet and the permanent magnet.

Abstract: A method and apparatus for optically isolating multiple core optical fibers while at the same time substantially reducing polarization mode dispersion, is disclosed. A multiple core fiber is optically coupled to optical birefringent elements, reciprocal and non-reciprocal rotators, and through a lens assembly to a multiple core optical fiber output.

Abstract: A spatial light modulation device is formed by creating forming an electromagnetic field within a substrate with at least one movable element, fixedly attached to the substrate at a first end, from a soft magnetic material with an anisotropic stress created within the movable element such that the element exists in a first position as a result of the anistropic stress and an actuating device comprising a magnetic layer placed within close correspondence with the soft magnetic material for placing the soft magnetic material into a second position.

Abstract: An object is to provide a magnetic garnet material, even if a thickness of an element is made thin, in which a sufficient Faraday rotation capacity can be obtained, a magnetic field for saturation can be controlled to be less than 200 (Oe), and a magnetic compensation temperature can be controlled to be less than 0° C. as well as to provide a Faraday rotator which can be made thin, suppresses a manufacturing cost and achieves a high yielding. The above object can be achieved by a magnetic garnet material known as the general chemical formula BixYbyGdzM13-x-y-zFewM2uM35-w-uO12 and the Faraday rotator using the above material. However, M1 is more than one kind of chemical elements which can replace Bi, Yb or Gd, M2 is more than one kind of non-magnetic chemical elements which can replace Fe, and M3 is more than one kind of chemical elements which can replace Fe and M2. Further, x, y, z, w and u respectively satisfies 1.0≦x≦1.6, 0.3≦y≦0.7, 0.9≦z≦1.6, 4.0≦w≦4.3 and 0.7≦u≦1.0.

Abstract: An integrated micro-optical system includes at least two wafers with at least two optical elements provided on respective surfaces of the at least two wafers. An active element having a characteristic which changes in response to an applied field may be integrated on a bottom surface of the wafers. The resulting optical system may present a high numerical aperture. Preferably, one of the optical elements is a refractive element formed in a material having a high index of refraction.

Abstract: A torsional micro-mechanical mirror system includes a mirror assembly rotatably supported by a torsional mirror support assembly for rotational movement over and within a cavity in a base. The cavity is sized sufficiently to allow unimpeded rotation of the mirror assembly. The mirror assembly includes a support structure for supporting a reflective layer. The support structure is coplanar with and formed from the same wafer as the base. The torsional mirror support assembly includes at least one torsion spring formed of an electroplated metal. An actuator assembly is operative to apply a driving force to torsionally drive the torsional mirror support assembly, whereby torsional motion of the torsional mirror support assembly causes rotational motion of the mirror assembly. In another embodiment, a magnetic actuator assembly is provided to drive the mirror assembly.

Abstract: Disclosed is a Faraday rotator capable of reducing the temperature dependence on a Faraday rotation angle, thereby enhancing the temperature characteristic, particularly, in a service environment in which the magnetization direction is variable, and an optical device using the Faraday rotator. The Faraday rotator includes a Faraday element which rotates the polarization plane of polarized light rays passing through the Faraday element when an external magnetic field is applied to the Faraday element.

Abstract: A specific polarized light component out of a light wave passed through a magneto-optic crystal (for example YIG) is extracted by a polarizer. The intensity of the light beam output from the polarizer depends on strength and direction of magnetic fields applied to the magneto-optic crystal. The magneto-optic crystal is applied with a first and a second magnetic field acting in directions different from each other and the strength of the composite magnetic field of them is set to exceed a predetermined value at all times. By varying at least one of the first and second magnetic fields, the attenuation factor in the magneto-optic crystal can be changed continuously and with good reproducibility.

Abstract: A magneto-optical light modulator includes a first polarizer, a transparent magneto-optical component including a magneto-optical film deposited on a surface of a substrate, and a second polarizer. The surface of the substrate includes features having a depth in a range of 0.1 &mgr;m to 5 &mgr;m. Side surfaces of the features are covered with the magneto-optical film to a thickness of 5 nm to 200 nm. Light flux from a light source passes through the first polarizer, the magneto-optical component and the second polarizer. Changes in incident light flux intensity can lead to rapid changes in the intensity of light flux transmitted through the magneto-optical light modulator.

Abstract: An optical device, such an as optical circulator or switch, which includes a birefringent tapered element, such as a birefringent wedge, positioned between first and second Faraday rotators. Light travels through the first Faraday rotator, the first birefringent tapered element and then the second Faraday rotator, in order, and along travel paths which are not parallel to each other.

Abstract: A magnetostatic wave device comprises a magnetic garnet single crystal film. The single crystal film magnetic garnet is represented by the general formula of Y3Fe5-x-yInxMyO12 (wherein M is at least one of Ga, Al and Sc, 0.01≦x≦0.45 and 0≦y≦1.2) and the Curie temperature is about 150° C. to 285° C.

Abstract: An optical modulator using an isolator, and an optical transmitter including the same are provided. The optical modulator modulates a carrier wave generated by an optical source according to a predetermined electrical signal. An isolator in the modulator includes a Faraday rotator in which the rotation angle of polarization is different according to the intensity of an applied magnetic field. The rotator controls isolation of an optical signal according to the polarization rotation angle and outputs a modulated optical signal. A magnetic field generator produces a magnetic field whose intensity is controlled by a predetermined electrical signal, and applies the produced magnetic field to the isolator. A signal generator supplies the electrical signal to the magnetic field generator and controls the intensity of the electrical signal.

Abstract: A method of fabricating a modulator for modulating an incident beam of light includes a substrate having a cavity formed therein and a plurality of spaced-apart deformable elements formed in the cavity. The deformable elements each has a base layer, a poled magnetic layer formed in the base layer and a first light reflection layer deposited on the magnetic layer for reflecting an incident beam of light. Between adjacent deformable elements on the base of the cavity is arranged a second light reflection layer. A conductive element formed in the substrate electro-magnetically energizes the deformable elements to deflect in the cavity. Incident light passing through each one of the first light reflection layers is caused to destructively interfere with light reflected from the second light reflection layers thereby causing modulation of the incident light.

Abstract: According to the present invention, a hybrid magnetic substrate is provided, which includes: a magnetic substrate; and a holding substrate directly bonded to the magnetic substrate through at least one of a hydrogen bond and a covalent bond. Furthermore, a method for producing a hybrid magnetic substrate having the magnetic substrate and the holding substrate is provided, which includes the steps of: cleaning a surface of the magnetic substrate to be bonded and a surface of the holding substrate to be bonded; allowing the cleaned surfaces to be subjected to a hydrophilic treatment; and attaching the surfaces, which are subjected to the hydrophilic treatment, to each other to directly bond the magnetic substrate to the holding substrate.

Abstract: An optical switch includes a light emitter for emitting light and light receivers. A reflector is used for changing a path of light emitted from the light emitter. The reflector is held by a permanent magnet having first and second magnetic poles of opposite polarities. A supporting member is provided for the reflector and the first permanent magnet so that the reflector and the first permanent magnet can move between a first position and a second position. In the first position, the reflector and the first permanent magnet interact so the emitted light travels into one light receiver of the light receivers. On the other hand, in the second position, the reflector and the first permanent magnet interact so the emitted light travels into another of the light receivers. The switch further includes an electromagnet for generating first and second magnetic fields selectively for moving the reflector and the first permanent magnet between the first and second positions.

Abstract: A modulator for modulating an incident beam of light uses a substantially planar light reflection surface formed by a light reflection layer associated with a plurality of deformable elements and a light reflection layer associated with a plurality of fixed elements. The fixed and deformable elements are arranged in a cavity of a substrate supporting the modulator. Light is modulated when a current is applied to a conductive element operably associated with the deformable elements causing the light reflective layer associated with the deformable element to deflect towards the base of the cavity from its substantial planar relations with the light reflecting layer of the fixed element.

Abstract: An n by m array of lenses layer where n is greater than 1 and m is greater than 1 is disposed on a combination of layers comprised of a first walk-off layer, a first non-reciprocal rotator layer, a first half-wave plate layer, a second half-wave plate layer, a second walk-off layer, a second non-reciprocal rotator layer, and a mirror layer. A method of forming optical p by q structures, where p is greater than 1 is provided. An n by m array of lenses layer where n is greater than 1 and m is greater than 1 is disposed on a combination of layers. The combination of layers is formed of the layers described above. An n by m structure comprising the array of lenses and the combination of layers is formed which is then divided into p by q structures having a p by q array of lenses layer, where p is greater than 1. Preferably p by 1 optical circulator strips are formed. Preferably all layers are formed by lithographic methods. The n by m array of lenses can be formed by reactive ion etching.

Abstract: An integrated micro-optical system includes at least two wafers with at least two optical elements provided on respective surfaces of the at least two wafers. An active element having a characteristic which changes in response to an applied field may be integrated on a bottom surface of the wafers. The resulting optical system may present a high numerical aperture. Preferably, one of the optical elements is a refractive element formed in a material having a high index of refraction.

Abstract: A reflective Faraday-based optical system is formed to include a partially transmissive optical reflector so that a portion of the optical signal propagating through the system will not be reflected but instead used as an input signal to a monitoring system. The partially transmissive reflector is configured to transmit only a relatively small portion of the optical signal (about 1-10%) so that the performance of the system is not affected. The optical monitoring arrangement may comprise one or more photodetectors, optical fibers, or other optical components for capturing the transmitted signal and converting into an electrical representation that can be evaluated to monitor the power in the optical signal.

Abstract: An optical magnetic field sensor probe for detecting a magnetic field to be measured as an output light intensity, by disposing a polarizer, a magneto-optical device, and an analyzer mutually different in the transmission and polarization direction with respect to said polarizer, along the running direction of light, has an input optical fiber for feeding into to said polarizer through a first lens, and an output optical fiber for emitting an output light from said analyzer through a second lens, wherein said input optical fiber, said first lens, said magneto-optical device, said second lens and said output optical fiber are composed in a confocal optical system, and said first lens and said second lens are drum lenses.

Abstract: The fiber optic transducer may take the form of a current sensor, and includes a first light path which is defined by a light transmitting element (19) and a second light path which is defined by a coil (10) of optical fiber (11). The coil-forming optical fiber ( 11) has a length which is significantly greater than that of the light transmitting element (19). A modulated light source (14) is provided for directing light simultaneously into both the first and second light paths. Also, the transducer includes detector/processing circuitry (15 to 17 and 20 to 24) for detecting light exiting from the light paths during successive time periods that include first and second time intervals t.sub.1 and t.sub.2.

Abstract: A low magnetic saturation type bismuth-substituted rare-earth iron garnet crystal film of the invention is grown on a substrate of (111) garnet single crystal (GdCa)3(GaMgZr)5O12 by using a liquid phase epitaxial method. This single crystal has a lattice constant of 1.2497.+-.0.0002 nm and has a chemical structural formula expressed byTb.sub.3-x Bi.sub.x Fe.sub.5-y-z Ga.sub.y Al.sub.z O.sub.12wherein x has the range 1.25<.times.<1.40, y+z has the range 0.50<y+z<0.65, and z/y has the range 0.45<z/y<0.75.

Abstract: A modulator for modulating an incident beam of light includes a substrate having a cavity formed therein and a plurality of spaced-apart deformable elements formed in the cavity. The deformable elements each has a base layer, a poled magnetic layer formed in the base layer and a first light reflection layer deposited on the magnetic layer for reflecting an incident beam of light. Between adjacent deformable elements on the base of the cavity is arranged a second light reflection layer. A conductive element formed in the substrate electro-magnetically energizes the deformable elements to deflect in the cavity. Incident light passing through each one of the first light reflection layers is caused to destructively interfere with light reflected from the second light reflection layers thereby causing modulation of the incident light.

Abstract: A specific polarized light component out of a light wave passed through a magneto-optic crystal (for example YIG) is extracted by a polarizer. The intensity of the light beam output from the polarizer depends on strength and direction of magnetic fields applied to the magneto-optic crystal. The magneto-optic crystal is applied with a first and a second magnetic field acting in directions different from each other and the strength of the composite magnetic field of them is set to exceed a predetermined value at all times. By varying at least one of the first and second magnetic fields, the attenuation factor in the magneto-optic crystal can be changed continuously and with good reproducibility.

Abstract: The present invention provides an optical device making use of a magneto-optical effect. The optical device comprises: a reflector for reflecting an input beam as a reflected beam; a magneto-optical crystal provided so as to pass the input and reflected beams; a first unit for applying a magnetic field to the magneto-optical crystal; and a second unit for varying the magnetic field in accordance with a control signal. The configuration described above allows a small magneto-optical crystal to be used and, thus, a small-size and a low-cost Faraday rotator to be provided. By adding a polarizer to such a Faraday rotator, a variable optical attenuator can be obtained. In particular, by employing a wedge plate as the polarizer, a polarized-independent optical attenuator can be provided.

Abstract: An optical device which can be used as a Faraday rotator which can provide an arbitrary Faraday rotation angle in accordance with a positional condition. The optical device includes first and second ports, magneto-optical crystal, and a unit for applying a magnetic field to the magneto-optical crystal. The first port is positioned in a first region while the second port is positioned in a second region. The first and second ports are optically coupled by a light beam. The magneto-optical crystal is provided such that the light beam may pass therethrough. The unit for applying applies a magnetic field to the magneto-optical crystal so that magnetization of the magneto-optical crystal may have a given distribution in a plane substantially perpendicular to the light beam.

Abstract: There is provided a magnetostatic wave device which operates even with a substitution R, A:YIG having a small film thickness and which has a wider operational frequency band. A magnetostatic wave device comprising a magnetic garnet film is provided which is made of a material expressed by a general formula: (Y.sub.1-r R.sub.r).sub.3 (Fe.sub.1-a A.sub.a).sub.5 O.sub.12 where R is at least one selected from among La, Bi, Gd and Lu; A is at least one selected from among Al, Ga, In and Sc; r and a are within the ranges 0.ltoreq.r.ltoreq.1 and 0.ltoreq.a<1, respectively; and r and a can not be zero at the same time. Further, the crystal structure of said magnetic garnet film is a superlattice.

Abstract: An apparatus which attenuates a light signal polarized in a first direction. The apparatus includes a polarization rotation unit and an output unit. The polarization rotation unit rotates the polarization of the light signal to produce a polarization rotated light signal having a polarization component in the first direction and a polarization component in a second direction which is substantially 90 degrees with respect to the first direction. The output unit passes, as an output signal, the polarization component in the second direction of the polarization rotated light signal and blocks the polarization component in the first direction. The polarization rotation unit includes an electromagnet and a permanent magnet which apply magnetic fields in specific directions with respect to the light path. Various yoke constructions are provided for the electromagnet and the permanent magnet.

Abstract: An optical isolator comprises two polarizers arranged before and after an optical rotator and a magnet surrounds the optical rotator. The magnet may generate a magnet field with a direction in spatial space parallel to the propagation direction of light traveling in the optical rotator and a strength sufficient to rotate the light to a predetermined rotation angle. Preferably, the polarizers are birefringent wedges of identical shape and optical properties. The magnet in accordance with the present invention may have a pair of magnetic adapters to generate the desired direction and strength of magnetic field. The direction of magnetic field varies in three-dimension space as the magnet is adjusted. The present invention provides an optical isolator of high isolation for high-volume mass production at a low cost. In particular, it may be easily operated at different wavelengths to achieve desired isolation without sacrifice of other optical properties of the optical isolator.

Abstract: Methods for preparing homogeneous magnetic fluid compositions capable of forming ordered one dimensional structures or two dimensional lattices in response to externally applied magnetic fields are disclosed. The compositions are prepared using improved co-precipitation methods in which the steps of the procedure have been tuned to reduce sample heterogeneity. Fe.sub.3 O.sub.4 particles are coated with a surfactant and dispersed in a continuous carrier phase to form these homogeneous magnetic fluid compositions. The ability of these compositions to generate ordered structures can be tested by holding a magnet near a thin film of the compositions and observing the formation of colors in the region near the magnet. Methods for controlling the characteristic spacing of the ordered structures formed by the composition also are disclosed.

Abstract: Methods for preparing homogeneous magnetic fluid compositions capable of forming ordered one dimensional structures or two dimensional lattices in response to externally applied magnetic fields are disclosed. The compositions are prepared using improved co-precipitation methods in which the steps of the procedure have been tuned to reduce sample heterogeneity. Fe.sub.3 O.sub.4 particles are coated with a surfactant and dispersed in a continuous carrier phase to form a homogeneous magnetic fluid composition. The ability of the composition to generate ordered structures can be tested by holding a magnet near a thin film of the compositions and observing the formation of colors in the region near the magnet. Methods for controlling the characteristic spacing of the ordered structures formed by the composition are also disclosed.

Abstract: An image pickup apparatus includes an image pickup unit in the form of a hollow ball having an image sensor inside thereof and a lens for focusing an optical image onto the image sensor, a first magnetic member fixedly attached to the image pickup unit, a holder for rotatably holding the image pickup unit, a second magnetic member for magnetically attracting the first magnetic member, and a mover for moving the second magnetic member to thereby rotate the image pickup unit so that the lens orients in a desired direction.

Abstract: A polarizing plate includes a polarizing layer for controlling a light and producing a polarized light, the polarizing layer having a particle dispersing medium with a property of light transmission and bar-like polarizing particles which are dispersed in the particle dispersing medium and arranged in a constant direction with a magnetic field, where each of the bar-like polarizing particles is provided with a bar-like ferromagnetic particle of chromium dioxide, whose surface is coated with a conductive film.